The Russian foreign affairs ministry says the "accusations" from the Joint Investigation Team probing the destruction of the Boeing 777-200ER over Ukraine, are "unfounded".

It adds that the conclusions are "aimed at discrediting our country in the eyes of the international community".

Investigators unveiled in-depth evidence, during a 24 May briefing, that the weapon – a Buk missile on a mobile transporter – was originally part of a military convoy from the 53rd anti-aircraft missile brigade in Kursk.

The ministry says the Russian side has not finished examining requests for legal assistance from the Dutch prosecutor in the case.

"Nothing was said [during the briefing] about the assistance we provided during the investigation," it states, adding that the investigators "forgot to mention" Russia's hosting of Dutch investigators in Moscow, and its declassification and supply of technical data on Buk missiles.

Dutch chief prosecutor Fred Westerbeke said, during the briefing, that circumstances "remain difficult" for the investigators.

"Part of the information required, which is mostly of foreign military origin, is classified," he said. "Getting this information takes time, consequently. And the investigation area in eastern Ukraine is still inaccessible to our investigating team."

The Russian ministry mentions a failure to acknowledge missile manufacturer Almaz-Antey's experiment, conducted in October 2015, during which a warhead was detonated against an Ilyushin Il-86 cockpit to highlight differences compared with the damage inflicted on MH17.

Russian authorities have supplied radar data – which, the ministry says, "cannot be tampered with or altered" – to the inquiry. But the ministry says this did not change the direction of the investigation.

The probe has previously used this data to show that there were no other aircraft in the vicinity of MH17 at the time it was destroyed, ruling out an attack from a fighter, and also explained why a Buk missile would not necessarily appear on the radar trace.

But the foreign ministry says the findings of the investigators "cannot be characterised [as anything but] absolutely untenable".

"All this only confirms our earlier expressed concerns about the bias and one-sidedness of the ongoing investigation," it states. "Nonetheless, we will continue to provide assistance so that the truth about the crash of flight MH17 is established, and the true perpetrators are brought to justice."